Thermionic tube construction



Patented Dec. 26, 1933 PATENT. 0 m:

THERMIONIC T BE 'ooNs'rRoo'rIoN Henry W.

signor to Rogers ronto, Ontario, Canada tario, Canada a corporation of On- Application February 13, 1930. Serial No. 428,103

' 1 Claim. (01. 250-275) My invention relates to the construction of thermionic tubes such as are used in radio communication and .pertains particularly to that class of such tubes which employ indirect heated or sleeve cathodes, the so-called alternating current tubes. 1

One of the principal objects contemplated by my invention resides in providing atube con-' struction in which the fabrication is simple, rugged, and may be cheaply accomplished.

Another object contemplated by my invention comprises producing a type of tube construction which lends itself readily to rapid fabrication by automatic machinery.

Another object contemplated by my invention consists in providing a type of tube construction which in a greater measure than heretofore insures uniformity of product in mass production.

I accomplish these and other desirable features which will hereinafter be pointed out and described by reducing the partsor elements of a heater type tube to a minimum through employing elements simultaneous for dual purposes. In other words, I eliminate, all electrode supports which do not function also as conducting terminals in combination with other novel features as shown in the accompanying drawing which forms a part of this specification and inwhich like reference numerals designate corresponding parts throughout the several figures. 1

In the drawing, Fig. 1 is a broken partially sectioned elevation of a thermionic tube constructed in accordance with my invention.

Fig. 2 is a broken section of the cathode and heater assembly.

Fig. 3 is a broken plan view of the tube shown in Fig. l.

Referring now particularly to Fig. 1, my invention comprises the usual glass envelope 7 1 to which is attached a terminal base 2 provided with five contact pins 3, 4, 5', 6, and '7, which make contact with their respective associated electrodes within the envelope; The stem within the envelope terminates in a press 8, which supports five supportingand conducting standards 9, 10, 11, 13, and 14. Standard 9 is electrically connected with one of the contact pins as 3 and bears attached thereto the anode 22. ,Standard 14 is connected electrically with one of the contact pins as 7 and bears attached thereto by means of the branch 15 the grid 19. Standard 10 is connected to contact terminal 4 while standard 11 is connected to contact pin 5. These standards serve to support, as shown, a heater filament 23 which supports an insulating member of lava or tion to have the required stiffness. However, the

.is placed in porcelain 21, which in turn supports the sleeve cathode or emitter 20. The contact of the cathode 20, usually termedthe sleeve tail, is taken from the lower end ofthe cathode and is connected to standard 13, which is in turn electrically connected with the remaining contact pin 6. There is also attached to the sleeve cathode 20 a support 12 in which the usual ,getter is placed. It will be noted that each of the standards serves as a sole support for their associated electrodes, as well as electrical conducting leads therefor.

An insulating member 18, preferably of mica, is provided with apertures; one for the cathode 20, two for the grid 19 and one for the anode 22 and the standards 14, 9, and15, as well as the cathode 20 are extended in order to protrude through the apertures provided in the member 18. The member 18 is held in position on the standards 9, and 14:by means of metallic clips 16 and 1'? which pass over the ends of the member 18 and are welded to the standards 14 and 9 re-' spectively.

It will be noted that the insulating member 18 serves in no sense as a support for the electrodes but merely as a means for maintaining the rela-' tive positions of the electrodes. This, of course, could also be accomplished without the use of member 18 by constructing the supporting standards and heating filament of sufiicient cross sec- 5 construction shown is preferred.

The construction just described lends itself admirably to mass production by automatic machinery because the sleeve tail" of the cathode, being taken from the lower end or extremity of the cathode permits the entire heater and cathode assembly being mounted on the standards 10, 1'1, and13, provided in the press, before the grid and anode are assembled. After the heatercathode is attached to the stem, the grid, which has previously been welded to the standard 15, positionover the cathodeand the extremity of the standard 15 is welded as shown in the figure to standard 14. After the grid'is in position the anode is slipped over the grid and welded to standard 9. Thereafter the positioning member 18 is placed in position and clips 16 and 17 are welded to standards 14 and 9, respectively. It. will be noted that the assembly is simple, straight-forward, and that it eliminates all unnecessary elements; that it provides no electrode of the electrodes is pre-determined and maintained at a definite value; all features permitting mass production with a high probability of uniformity of product. 7

Having thus described my invention, what I claim and desire to secure by United States Letters Patent is as follows:

A thermionic tube of the indirectly heatedcathode type comprising, a press, a cathode and heater therefor, a sleeve tail extending from the lower extremity of said cathode adjacent said press and serving as the sole terminal for said cathode, a conductor extending through said to r 

